As is well-known, vehicle roofs have an interior trim which must possess certain minimum qualities, such as being self-supporting, readily adaptable to the different shapes of vehicle roofs, lightweight, endowed with good sound absorption and heat insulation properties and having an external appearance that is pleasing to the eye and to the touch.
For this purpose, multi-layer trims are normally used consisting of one layer that may be composed of different substances, such as rigid or flexible foams, fibre glass, thermoplastic or vegetable-based materials, paper or plastic sheets, adhesives and, lastly, a light fabric outer layer that forms the external or decorative face.
This trim is mounted on the metal body frame of the vehicle and then the interior accessories, such as sun visors, grab handles, lights, head airbag, speakers, electrical wiring, etc. are fitted on it, all these operations being performed manually from inside the vehicle, which makes the complete installation of the roof rather a complicated process.
Car makers have therefore been asking their suppliers not only for roof trims, but also that the roof trim should form a pre-assembled unit, including the different roof accessories, such as sun visors, grab handles, light units, electrical wiring or head airbags, in which the assembly of all these items is carried out at the supplier's plant. These modular trims include a series of clips or quick fasteners that may be installed on the actual body: frame or roof of the vehicle, this operation generally being performed by offering up the trim with the pre-assembled accessories through the vehicle windscreen and proceeding to fasten the trim quickly from inside the vehicle itself by means of the above-mentioned clips.
In this way, the trim is installed with at least some of its accessories pre-fitted in a single operation, an installation operation that is carried out quickly and simply by means of the afore-mentioned fastening clips.
This type of solution may be observed, for instance, in the following PCT patents of the same applicant: WO98/48179, WO98/47741, WO99/43517, ES99/00305, ES01/00391 or ES01/00924.
These patents, however, only offer a partial answer to the needs of car makers, as they are not capable of adapting to the wide range of solutions required by such external items as sun roofs or panoramic roofs, where it would be an advantage if the trim could include all the accessories or modifications needed for it to be able to be used in all cases.
A more highly developed solution is the one in which the roof trim includes, besides the above-mentioned accessories, the roof panel and even the sun roof or panoramic roof. This assembly, which may be called a roof module, can be installed in a downward direction, so that the roof module panel first rests and is then fastened to the perimeter frame, which would be an integral part of the vehicle.
This type of installation has major drawbacks as the dimensions of the roof trim are considerably larger than those of the actual roof and, consequently, larger than those of the opening left in the top of the vehicle, so inserting it through the upper hole in the top of the vehicle body is extremely complicated.
On top of this it should be pointed out that the roof trims are very fragile and, if not bent properly, may break or have cracks or distortions that are still there after installation, imperfections which are unacceptable today in the automobile industry.
To overcome this problem the roof trim may be divided into two or more parts which are assembled separately on the vehicle. This system has the disadvantage that the complete module composed of the roof panel, the trim and the accessories cannot be installed in a single operation, so the advantages of modularity sought in systems of this type are lost.
An attempt may also be made to bend the trim during the process of installation on the vehicle, but this calls for special highly flexible trims, which, besides being higher priced and heavier, have poorer sound absorbing properties. Furthermore, very expensive manipulators have to be used for bending the trim during assembly on the vehicle.